This innovation concerns the design of a device to be applied to one of support brackets of any sliding door or shutter, particularly furniture or sliding partitions, in order to cushion their movement, near a point of arrival at ends of gaps or openings that these shutters open or close.
The use of sliding doors or glass partitions, for example for furniture, display windows, fitted wardrobes or sliding partition walls, is particularly advantageous, compared to hinged systems, due to the fact that it allows for much larger closing and opening surfaces to be designed, without having to provide large spaces in front to allow for opening and closing.
According to a well-known technique, precisely due to their considerable size, any sliding door or glass partition is usually supported by a pair of brackets or carriages fixed at its upper edges. Each carriage has a corresponding sliding wheel, whose race is joined to a track. The track is mounted on the upper surface of the item of furniture or the void to be closed, whilst a striker or a lower guide, essentially parallel to the upper track, typically forces the side opposite the shutter itself to always remain in a vertical position, even when sliding, using countless structural solutions proposed and illustrated, for example, by EP 0 001 956 dated 1978 or by U.S. Pat. No. 5,247,763 dated 1990 or by EP 0 567 262 dated 1992.
This same well-known technique in fact, usually requires a pair of voids placed side by side to be closed by a pair of shutters; these, sliding on corresponding parallel tracks and guides placed side by side, allow one of the two voids to be fully opened, overlapping the opened shutter onto the shutter of the closed void, whilst, when both shutters are closing the corresponding voids, they are in any case mounted on two parallel levels, with the edge of one of their central sides ideally aligned or, more often, slightly overlapping the edge of the other shutter.
All these well-known solutions typically provide for that the void can be closed and opened by pushing or drawing the shutter along its track, with a physical force proportional to the size and therefore the weight of the shutter itself.
In order to prevent an excessive force pushing the shutter hard against the opening or closing doorstop, the same well-known technique envisages the application of “stoppers” or catches with narrow seat or section, within which a latch can be slotted for the travelling shutter that, due to friction, can slow down its drive, before reaching its doorstop.
This method, however, has been shown to be rather ineffective, both due to wear over time and, especially, when the shutter is pushed or drawn with excessive force, given that the narrow section of the catch does not manage to retain the shutter latch, which rides over said “stopper”, bouncing against the doorstop and, tending to travel back, partly obstructing the void to be opened, with subsequent manual adjustments to the position of the shutter itself, as well as frequent damage due to vibration from parts being struck.
A more recent technique aims to overcome this disadvantage, cushioning the end part of the shutter travel, when it is near full opening or closing, exploiting the absorption capacity of an elastic compression device, which is put into contact with the edge of the travelling shutter, in order to then use its reaction force to be discharged gradually into the chamber of a special piston connected to it, for example a pneumatic one, as proposed by Patents EP 1 348 828 and EP 1 426 535 for each of the two sides of the shutter itself.
Nevertheless, each known cushioning solution, among those mentioned above, has highlighted problems and disadvantages that limit their effectiveness and reduce their use to a few simple cases of furniture or sliding partitions that are not subject to heavy use.
A first disadvantage is the fact that, as is well-known, pistons have a life limited by the fastness to hold their seal, therefore requiring a foreseeable scheduled maintenance programme that does not seem to be justified, for example for furniture doors.
A second disadvantage of linking elastic devices and pistons is that, with uncalibrated collisions and thrusting, the piston tends to deform and in any case deteriorate even more often than expected, impacting further on the limited life of the item of furniture or shutter to be closed and opened.
Another disadvantage of this recent technique is the fact that, as it is well-known, a normal traction spring does not absorb and transmit a thrust uniformly, but proportionally to its expansion or extension, with a consequent increase in the force required to push the shutter at different gap opening or closing positions.
Finally, all the well-known forms of cushioning with springs and pistons, as above, at most allow the application of only two shutters, given that the devices are applied directly onto the track, thus preventing the translation of the cushioning devices of a possible third sliding shutter.